Heating system and control means therefor



y 1936- L. w. EGGLESTON 2,042,217

HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed Feb. 20, 1954 a Shee's-Sheet 1 MINIMUM! INVENTOR May 1936- w. EGGLESTON 2,042,217

HEATING SYSTEM AND CONTROL MEANS THEREFOR Filed Feb. 20, 1934 :5 Sheets-Sheet 2' INVE NTOR L. w. EGGLESTON 1 17 HEATING SYSTEM AND CONTROL MEANS THEREFOR May 26, 1936.

Filed Feb. 20, 1934 3 Sheets-Sheet 5 I INVNTOR @M gw A RNEY Patented May 26, 1936 uNrrEo STATES PATENT GFFICE HEATING SYSTEM AND CONTROL MEANS THEREFOR Application February 20, 1934, Serial No. 712,117

18 Claims.

My invention relates to new and useful improvements in heating systems and means for controlling the same. The system is particularly adapted for use in connection with the heating of residences or apartments and has for one of its objects the provision of means for controlling the heating apparatus in accordance with the demands of separate rooms or zones to be heated.

Another object is to provide a system in which overheating of the room or zone will be prevented.

Another object is to provide a heating system in which means for controlling the supply of the room or zone heating medium serves to control the heating apparatus.

Another object is to provide novel motor means for actuating the valves or dampers embodied in the system.

Another object is to provide a valve or damper control means which is operable to control means for regulating the heating apparatus.

The invention consists in my improved system and the interrelated elements comprising the same, together with the novel construction embodying certain of the elements thereof, all of which will be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of this specification, I have fully and clearly illustrated a preferred embodiment of my invention, in which drawings-- Figure 1 is a view, partly diagrammatic, of my heating system and the control means therefor;

Fig. 2 is a view in front elevation of a motor embodied in my system;

Fig. 3 is a top plan view of the device shown in Fig. 2;

Fig. 4 is a view in section on the line 4-4 of Fig. 3; d

Fig. 5 is a view in side elevation of the motor or device looking from the left toward the right of Fig. 3;

Fig. 6 is a detail view ofa heating element forming a part of the motor,

Fig. '7 is a wiring diagram of a circuit including the heating element, and

Fig. 8 is a detail view on the line 8-8 of Fig. 2.

Referring to the drawings by characters of reference, I designates generally, a heating apparatus such as a hot air furnace which may be positioned in the basement 2 of a house or other structure to be heatedthereby. The furnace I is shown'as of the coal-fired type having a draft inlet damper 3 controlling an ash pit air inlet and having a check damper l controlling the inlet of air to the smoke pipe 5 or outlet duct from the combustion chamber of the furnace. The dampers 3 and 4 comprise means-for regulating 5 the heating apparatus and particularly operate to regulate the temperature to which the medium heated by the furnace is subjected, and therefore the dampers serve to control or regulate the temperature of the medium heated by the furnace. 10 The furnace is provided with a dome or bonnet 6 to which the heating medium or the heat transferring medium is supplied in the usual manner and from which conduits or ducts designated 1, 8 and 9 lead to the regions or zones to be heated. 15 The ducts l and 8 are shown as opening into the rooms or zones [0, II respectively which are separated by a wall or partition I2. Although'the ducts are shown as having their outlets l3 opening into the rooms I0, ll through the floor l4, it 20 is obvious that the ducts may discharge into the rooms through a side wall thereof as desired. In the room It) there is a thermostat l5 responsive to temperature of the room air and which is preferably mounted on the partition l2. The ther- 25 mostat [5 may be of any of the well known types on the market having switch means closed by a temperature responsive element when the room temperature is below the desired degree for which the thermostat is set to operate. that is, when 30 the thermostat is unsatisfied or calling for heat. The thermostat l5 actuates an automatic control means [6 which operates a valve or damper l'l controlling flow of the heat transferring medium through theduct 1. The motor means I6 is connected by lead wires l8,- H) to the secondary side 2|] of a transformer having its primary side 2| connected to a source of current supply. From the other side of the transformer secondary 20 y a lead wire 22 extends to one contact of the switch 40 means of the thermostat l5. From the other contact of the thermostat switch means a lead wire 23 connects with the motor means sothat the thermostat, the motor means and the trans-, former secondary are in seriescircuit. The mo- 5 tor means It is provided with an electric switch means 24 which is operated by the means l6 when the damper I1 is moved to open position to close the circuit of an automatic control means 25 such as a heat motor for actuating the regulating 60 means of the apparatus. The switch means 24 is connected by a lead wire 26 to the motor control means 25 and from the means 25 a lead wire 2! connects to the secondary 28 of a transformer having its primary 29 connected to a source of current supply. In the lead wire 21 there is a safety switch 30 which is responsive to temperature of the heat transferring medium in the bonnet 6. Switch 38 comprises a switch arm 3| operable by any suitable heat responsive means such as a bi-metal element, or the like, to make and break circuit through the wire 21, the blade 3| being shown by dotted line in its circuit breaking position. The switch 39 is preferably set to break circuit at a predetermined maximum bonnet temperature so as to actuate the regulating means of the heating apparatus to stop further heating of the heat transferring medium and to shut down'the heating apparatus. From the other side of the transformer secondary 28 a lead wire 32 connects to the switch means 24. The motor means 25 is provided with apivoted lever arm which has its opposite ends connected by connecting means 34, 35 such as chains to the check and draft dampers 4, 3 respectively. The chains 34 and 35 are preferably strung over pulleys 36 preferably supported by the beams 31 which support the floor M. The chains 34 and 35 are connected to their respective dampers in the usual manner such that the damper 3 is opened when the damper 4 is closed and vice versa, and also so that the dampers may be simultaneously closed.

'The duct 8 is provided with a valve or damper 38 operated by an automatic control means v39 similar to the means l6. The control means 39 is actuated in response to operation of a room thermostat 49 similar to the thermostat I5 and mounted on a side wall 4| of the room II. One side of the switch of thermostat 40 is connected by a lead wire 42 to the motor control means 39 which is connected by a lead wire 43 to the lead wire l8 connected to the transformer secondary 29. The other side of the switch of thermostat 46 is connected by a lead wire 44 to the lead wire 22 which extendsfrom the other side of the transformer secondary so that the room thermostat 48, the motor means 39 and the transformer secondary 20 are in series circuit. It will be noted that the thermostat I5 and motor means |6 are in parallel circuit with the thermostat 48 and its motor means 39. The motor means 39 is provided with a switch means 45 which is moved by the motor means 39 to closed circuit position when the damper 38 is moved to open position. The switch means is provided with a lead wire 46 which connects to the lead wire 26 for the motor means 25 and is also provided with a lead wire 41 which connects to the lead wire 32 so that when the switch means 45 is closed, a circuit will be completed from the transformer secondary 28 through lead wire 21 and its switch 38 to the motor means 25 and thence via lead wires 26 and 46, the switch means 45 and lead wires 41 and 32 back to the transformer secondary 28.

In Figs. 2, 3, 4 and 5 I have shown in detail the preferred construction of the control means, designated I6, 25 and 39, which control means are of substantially the same construction. A supporting plate or base member 48 is provided having a down turned marginal flange 49 and to the underside of which is secured a heat operated motor. This motor comprises a casing 50 which is substantially cup-shaped, having a marginal surrounding flange 5| which seats against the underside of the plate 48 and which is engaged by nuts or bolts 52 which clamp the casing 58 tightly to the plate 48. Within the casing 56, there is an expansion chamber 53 having its top The bellows elein the top end of the casing 50, being sealed thereto and seating on an internal annular shoulder 56 formed in the side wall of the casing. The lower end of the bellows is closed and sealed by a head or end wall 5'! having a filler tube 58 extending upwardly therefrom. The head 51 supports a hollow thrust member or rod 59 which surrounds the tube 58 and which projects upwardly within the bellows and through an aperture 68 in the supporting plate 48. The lower end portion of the thrust member 59 is screw-threaded, as at 6|, to receive an adjustable collar or nut 62 having a circumferential, laterally projecting flange 63. Seated on the flange 63 is one end of a helical coil spring 64 which at its other end engages the supporting plate 48 seating in a recess formed in the underside thereof. The spring 64 is held under compression between the nut 62 and the plate 48 so that it acts to hold the thrust member 59 in engagement with the head 57 and determines the force in chamber 53 which will move the thrust member 59 upwardly. Secured to the top face of plate 48 there is a supporting member or bracket 65 which is preferably substantially U-shaped, having upwardly extending supporting arms 66, 61 which are substantially parallel to the front edge of the supporting plate 48. Extending through the supporting arms adjacent the upper end of the thrust member 59 there is a bearing shaft or rod 68 which serves to pivotally support a rocker or actuating member 69. The member 69 has front and rear depending side flanges 19, provided with aligned apertures to receive the shaft 68 and which are positioned between and substantially in engagement with the arms 66, 61 to prevent movement of the rocker member longitudinally of the shaft 68. The flange II extends into a longitudinal end slot 12 formed in the top end of the thrust member 59 and is pivotally secured therein and to the thrust member by a pivot pin l3. The underside of the flange 1| is inclined upwardly, as at 14, to provide a stop face or portion engageable with the plate 48 to limit downward movement of the thrust member 59 or counter-clockwise movement, facing Fig. 4, of the rocker member 69. The arm 61 has an inclined stop face or portion 15 engageable by a projecting lug or ear 16 on the member 69 to limit upward movement of the thrust member 59 or clockwise movement, facing Fig. 4, of the member 69. Supported on the forwardly projecting end 11 of the shaft 68 there is a lever arm or operating member 18 provided with a sleeve or hub I9 preferably journaled on the end portion l'l. The lever arm 18 is operatively connected to the rocker member 69 by a pin or projecting element 88 secured to the arm 18 and extending rearwardly into a downward open recess or notch 8| in the flange I8.

The pin 89 is held in engagement with the member 69 by a spring 82 coiled about the shaft 68 shaft 08 and is provided with a latch means to hold it against movement under the force of spring 84 and preferably in substantially horizontal position or midway of its range of movement. The latch means comprises a longitudinally movable pin or stop member 85 slidably supported in a bearing sleeve 86 secured in and extending transversely to the lever arm I8. The pin 85 is provided with a head or hand grip portion 81 by which it may be moved inwardly into holding position against the force of a coil spring 88 which surrounds the pin 85 and is held under compression between the head 81 and the arm I8 so that it normally tends to move the pin out of its holding position. The pin 85 is provided on its inner end with a flange 89 which engages the inner or rear end face of the sleeve 86 to prevent withdrawal of the pin 85 from the sleeve member 86. The pin 85 is movable into overlying frictional engagement with the top end of a stop member 90 which is vertically adjustable in the supporting plate 48. The pin 85 is held in frictional engagement with the post 90 under the force of spring 64.

The expansion chamber 53 is connected to a bulb element SI by means of a tube 92 of small bore. The tube 92 opens, as at 93, into the bulb element 9| through a bottom wall or head 04 which closes and seals the bottom end of the element 9|. The bulb element is housed within a casing 95 which serves to insulate the element 9| from the chamber 53 and which is rigidly secured to the underside of the supporting plate 48 by nuts and bolts, or the like, 98 engaging a marginal flange 91 on the casing 95. The tube 92 extends upwardly within the casing 95 and over the top edge thereof, as at 98, and thence downward to a point adjacent the bottom of the chamber 53, at which point it opensthereinto through a fitting element 99. The bulb element 9I is provided with an upper head or end wall I which closes and seals the top end of the bulb element. The bulb element isqsecured to the underside of the plate 48 by a screw IOI which extends through the plate 48 and is threaded into the head I09. The screwv IOI also serves to secure a pad or plate I02 of electric insulating material to the top face of the supporting plate 48. Supported by the pad or plate- I02 and projecting upwardly therefrom there are terminal or binding posts I03, I04. These posts are connected to the opposite ends of a heater coil I which surrounds the bulb element 9!, being suitably electrically insulated therefrom by a covering I06 of insulating material such as mica wrapped around the element 9! and underlying the coil I05. The lead wire which extends upwardly from the lower end of the coil is electrically insulated from the turns of the coil. by a glass tube I01. The binding posts I03 and I94 are provided with longitudinal bores I08 into which the end portions or lead wires of the coil I05 extend, being secured therein by set screws I09. The bulb element 9| and the chamber 53 are charged with a suitable volatile liquid such as acetone or alcohol, the liquid substantially completely filling the bulb element and chamber when the bellows has been extended to bring the stop portion I4 into engagement with the plate 48.

The control device also includes a switch means which is operated by the rocker member 89. This switch means comprises up r and lower vertically spaced switch blades H9, II provided with suitable contact elements or members carried by the free end portions of the switch blades. The blades H0, III are of resilient sheet metal and are rigidly secured by screws, or the like, I I2 to vertically spaced, metal conductor plates II2 fixed to a supporting block N3 of electric insulating material which is fixed to the top face of the plate 48 by a screw H4. The blades III, III] are connected by lead wires H5, H5 respectively to terminal posts H1, H8 carried by a pad or plate II 9 of electric insulatingmaterial secured to the top face of the supporting plate 48 by one of the bolts 52. The lead wires H5, H6 are secured to their respective conductor plates H2 by binding screws I20, I29 which are electrically insulated by washers I20 from the supporting plates H2 for blades H0, III respectively, see Fig. 8. The rocker member 69 is provided with an abutment I2I of electric insulating material which is engageable with the switch blade I I0 to move the blade IIO into engagement with the blade III to close an electric circuit. The abutment member I2I preferably actuates the switch means to make circuit substantially at the end of clockwise travel of the rocker member 09, overtravel of the rocker member after the blades are in engagement being permitted due to theflexibility of the blades. The control device is preferably provided with a supporting bracket I22 which is secured to the supporting plate 48 and by which the control device may be rigidly mounted in operative position.

The operation of my system and of the control means or device is as follows, the system having been wired to provide the circuits above described and the lever arms I8 of the motor means I5 and 39 respectively being connected by suitable operating linkage to their respective dampers I1 and 38: As shown, the thermostat 40 has been satisfied so that the circuit through the lead wires 42 and 44 controlled thereby is broken at the thermostat. Breaking of the circuit through the lead wires 42, 44 has broken the circuit from the transformer secondary 20- thereby deenergizing the heater coil I05 of the motor means 39. With the circuit broken through the heater coil I05, the vaporized liquid in bulb element 9i will condense and contract, permitting the spring- 94 of motor means 39 'to move the rocker member 69 and its lever arm I8 counter-clockwise thereby releasing the switch blade I I0 and moving the damper 38 to closed position. The breaking of circuit between the switch blades 9, III of the switch means 45 will not affect the motor means 25 as the circuit thereto is completed by a parallel circuit through the switch means 24 of the motor means I6. The thermostat I5 is unsatisfied and calling for heat as the room or'zone I0 is below the desired temperature. The circuit at the thermostat I5 is therefore closed through lead wires 22, 23 so that the heater coil I95 of the motor means I6 is energized by the transformer secondary 20. As the bulb element 9| heats up under the influence of coil I05, liquid will be forced through the tube 92 into the chamber 53 which will force the thrust member 59 upward. .This movement of the thrust member 59 will continue until the stop member I6 engages the stop face I5, when the lever arm '58 of motor means I8 will be in the position shown in Fig. 1. Movement of the lever arm I8 of motor means I6 to this position in which it will be held as long as current is supplied to the coil I05 acts through its connecting linkage to move the damper I! to open position and to move abutment member I2I into engagement with the switch blade II 6 to close the switch means 24. The circuit through lead wires 26 and 32 controlled by switch means 24 completes the 011- cuit from the transformer secondary 28 through the safety switch 30 and the heater coil I65 of the motor means 25. Energization o the motor means 25 acts as above described with respect to the motor means I6 to rotate the lever arm 18 of motor means 25 in a clockwise direction to the position shown, in which it will be held as long as the switch means 24 is maintained closed. With the lever arm I8 of motor means 25 in the position shown, the heating apparatus I will be regulated by the dampers 3, 4 to heat the heat transferring medium in the bonnet 6, that is, the lever arm I8 will pull on the chain 35 to open the .draft damper 3 and will release the chain 34 sufficiently to permit the damper 4 to by breaking the circuit from the transformersecondary 28 to the heat coil I65 of motor means 25 so that the spring 64 of this motor means will act through its lever arm I8 to pull on the chain 34 to open the check damper 4 and will release the chain 35 to permit the damper 3 to move to closed position thereby checking the fire and stopping further heating of the heat transferring medium in bonnet 6. When the bonnet temperature decreases sufficiently to permit closing of safety switch'30, the motor means 25 will again be energized to open the draft damper 3 and c ose the check damper 4 if either of the thermostats I5 or 40 is unsatisfied and. calling for heat. When the room thermostat I5 becomes satisfied and breaks circuit through the lead wires 22, 23 thereby deenergizing the heater coil I05 of motor means I6, then the spring 64 of this motor means will rotate its lever arm I8 to close the damper I1 and release its switch blade I I0 so as to open the circuit to motor means 25 through the lead wires 26 and 21. If the thermostat 40 is still satisfied so that the circuit is broken thereat through lead wires 42 and 44, then the heater coil I05 of motor means 25 will be deenergized and the spring 64 of this motor means 25 .will act through its lever arm 18 as above described to close the draft damper 3 and open the check damper 4. The latch means above described comprising pin is provided to permit manual control of the dampers 3, 4 when it is desired to stoke or fire the furnace. If the thermostats I5 and 40 are both satisfied, the draft damper 3 will be closed and the check damper 4 will be open as above described but it is desirable that the dampers both be in closed position during the firing operation. The furnace attendant may grasp the lever arm 18 of motor means 25 and manuallymove it against the force of spring 64 until the arm is in the position shown in Figs. 2 and 3, when the pin 85 may be pushed inwardly into overlying relation to the stop post and be manually so held while the lever arm is released to permit the spring 64 to hold the pin 85 frictionally in engagement with the stop post 90. After the firing operation is completed, the latch means may be manually released by rotation of the lever arm to lift the pin off of the post H 0 so that the pin 85 will be retracted by the spring 88. If the lever arm I8 of motor means 25 is left in this last position and not manually released, then if either thermostat I5 or thermostat 40 becomes unsatisfied and calls for heat so as to cause closing of the switch means 24 or 45' respectively, then the heater coil I 05 of the motor means 25 will be energized to move its lever arm I8 to the position shown in Fig. 1 thereby automatically releasing the latch means for retraction by the spring 88 so that the motor means 25 will again be in complete control of the heating apparatus and be operable to close the draft damper 3 and open the check damper 4, when thermostats I5 and 46 again both become satisfied. The post 90 of the latch means for the motor means I6 and 39 is preferably adjusted so that when in latched position the dampers I1 and 38 will be 15 held in open position and the switch means 24 and 45 will be closed by their respective rocker members 69. It is thus possible to manually regulate the heating apparatus to supply heat to either the zone ID or to the zone II independently of the thermostats I5 and 46 respectively,

in the event either thermostat should become inoperative. Under this condition with either of the switch means 24 or 45 latched in closed po sition, the heating apparatus would be under the control of the safety switch 30 which would operate through the motor means 25 to prevent overheating of the furnace I. Assuming the thermostats I5 and 40 to be operative, then ifthe lever arm 18 of either motor means I6 or 39 were manually latched in position to close the switch means 24 and 45 or either of them, the heating apparatus would be under control of the safety switch 30 and continue to supply heat until the thermostat controlling the latched motor means became unsatisfied, when it would close the circuit to the heater coil of the latched motor means and move the lever arm 18 sufficiently to release the latch pin 85 thereby when the thermostat again became satisfied permitting 40 the released lever arm to close its draft damper and open its switch controlling the motor means 25. From the foregoing description it will be apparent that a heating system is provided in which a heating apparatus is controlled in response to the requirements of separate zones or regions to be heated thereby. It will also be noted that operation of the safety means 3fl to stop or decrease heating of the bonnet 6 does not act to close the dampers I I or 38 so that the furnace is'cooled by the flow of the heat transferring medium passing thereinto and discharging through the ducts 7 and 8 thereby preventing injury to the heating apparatus which might result if the duct dampers were closed.

What I claim and desire to secure by Letters Patent of the United States is:

'1. A heating system comprising a furnace having a bonnet, a duct for conveying air from said 60 bonnet to a room to be heated, a damper in said duct, means acting to close said damper, an electrically energized motor operable when energized to overcome said closing means and having a lever arm operatively connected to said damper, a thermostat controlling the circuit of said motor and responsive to temperature in said room, an electric switch actuated by and upon movement of said lever arm to open said damper, electrically operated means having its circuit controlled by said switch and controlling the temperature of said furnace, and switch means responsive to the temperature of said bonnet and means.

2. A heating system comprising a heating apparatus having draft and check dampers, a motor having a lever arm, means operatively connectingsaid arm to said dampers, said motor comprising an expansion chamber having a movable wall, a bulb element communicating with said ,chamber, an electric heating element, for said bulb element, a thrust member operable by said wall, a pivotally supported member engaged by said thrust member, means operatively connecting said pivotally supported member and said lever arm, means controlling flow of the medium heated by said furnace, switch means operable by said controlling means and-controlling said heating element, and a thermostat responsive to temperature created by said furnace and controlling said controlling means.

3. A device of the character described, comprising a supporting member, motor means secured to the underside of said supporting member, said supporting member having an aperture therethrough, a rocker member pivotally mounted upon said supporting member, a thrust member extending through said aperture and operatively connecting said rocker member and said motor means, a lever having a fulcrum support, means connecting said rocker member and said lever, said last-named means including a spring to permit relative movement between said lever and said rocker member, and switch means operable upon operation of said lever.

4. A heating system comprising a hot air heating furnace for heating air to be supplied to a room or enclosure, a duct connecting the furnace bonnet to said room, a damper insaid duct, said damper having an arm, a switch operable by said arm, an electrically energized operating means for actuating said arm, switch means responsive to room temperature for closing the circuit of said operating means, and means controlled by said switch for regulating the rate of combustion in said furnace.

5. A heating system comprising a hot air heating furnace for heating air to be supplied to a room or enclosure, a duct outlet leading from the furnace bonnet, a damper in said duct, said damper having an arm, a switch operable by said arm, an electrically energized operating means for actuating said arm, switch means responsive to room temperature for closing the circuit of said operating means, and means controlled by said switch for regulating the rate of combustion in said furnace.

6. A heating system comprising a hot air heating furnace for heating air to be supplied to a room or enclosure, a duct outlet leading from the furnace bonnet, a damper in said duct, said damper having an arm, a switch operable by said arm, an electrically energized operating means carried by said duct foractuating said arm, switch means responsive to room temperature for closing the circuit of said operating means, and means controlled by said switch for regulating the rate of combustion in said furnace.

7. A heating system comprising a hot air heating furnace for heating air to be supplied to a room or enclosure, a duct leading from the furoperating means for actuating said arm, switch means responsive to room temperature for clos- 1 ing the circuit of said operating means whereby to actuate said first damper, and an electrically er controlled by said switch whereby furnace combustion is regulated in accordance with the position of said first damper.

8. A heating system comprising a heating apparatus operable to heat a heat transferring medium, a conduit to convey the medium to a region to be heated, a second conduit to convey the medium to a second region to be heated, a normally closed valve in said first conduit, a normally closed valve in said second conduit, a thermostat responsive to temperature in said first region, means operable by said thermostat to move said first valve to open position, means to control said heating apparatus and tending to move to a position to stop heating of said medium, means actuated'by said thermostat operated means to move said apparatus control means to supply heat to said medium, a thermostat responsive to temperature in said second region, means operable by said second thermostat to move said second valve to open position, said thermostat operated means being operated by said. last-named means to move said apparatus control means to supply heat to said medium, and means responsive to the temperature of said medium for' deenergizing said thermostat operated means whereby said apparatus control means will move to said position to stop heating of said medium.

9. A heating system comprising a furnace having a bonnet and having draft and check dampers, means continuously acting to move said draft damper to closed and said check damper to open position, motor means operable to overcome said means and reverse the positions of said dampers, a hot air duct leading from said bonnet to a room to be heated, a damper in said duct, means acting to close said duct damper, a thermostat responsive to temperature in said room, electrically energized means operable to overcome said duct damper closing means. and having its circuit controlled by said thermostat, said last-named means acting to move said duct damper to open position when said thermostat calls for heat, a switch controlling the circuit of said motor means and movable to closed position by and upon operation ofsaid electrically energized means, and means responsive to bonnet temperature operable to break the circuit of said motor means whereby'said continuously acting means will close said draft damper and open said check damper at a predetermined high temperature in said bonnet.

10. A device of the character described, comprising a supporting member, motor means car- 'ried by said member, a rocker member fulcrumed on said member, a thrust member operatively connecting said motor means to said rocker member, a lever having a fulcrum support, cooperable abutment means on said rocker member and said lever, and a spring having its opposite ends act- V ing on said lever and said rocker member to hold said abutment means in engagement and whereby said rocker member and said lever are relatively movable.

11. A device of the character described, comprising a supporting member, motor means carried by said member, a rocker member journaled on said member, a thrust member opera-tivelyconnecting said motor means to said rocker member, a lever journaled concentrically with said rocker member on said -supporting member, and a spring acting on-said lever and on said rocker energized operating means for said second dampmember, said spring serving to hold said lever to said rocker member for unitary movement, said lever being movable relative to said rocker member against the force of said spring whereby said rocker member and said lever are relatively movable.

12. A device of the character described, comprising a supporting member, motor means carried by said member, a rod mounted on said supporting member, a rocker member pivotally supported by said rod, a thrust member operatively connecting said motor means to said rocker member, a lever pivotally supported by said rod, a coil spring surrounding said rod and acting at one end on said rocker member and at its other end on said lever, and means to limit movement of said lever and said rocker member relative to each other by said spring whereby said rocker member and said lever are relatively movable.

13. A device of the character described, comprising a supporting member having opposed flanges, motor means carried by said supporting member, a shaft extending between and supported by said flanges, a rocker member having flanges receiving said shaft, a lever mounted on said shaft, said lever and said rocker member being relatively movable, stop means on said lever and said rocker member'to limit said relative movement in one direction, and a helical coil spring surrounding said shaft and holding said stop means in engagement.

14. A heating system comprising a furnace having draft and check dampers, a motor having a lever arm, means operatively connecting said arm to said dampers, said motor comprising an expansion chamber having a movable wall, a bulb element communicating with said chamber, an electric heating element for said bulb element, a thrust member operable by said Wall, a pivotally supported member engaged by said thrust member, means operatively connecting said pivotally supported member and said lever arm, and a thermostat responsive to temperature created by said furnace and controlling said heating element.

15. A heating system comprising a furnace having draft and check dampers, a motor having a lever arm, means operatively connecting said arm to said dampers, said motor comprising an expansion chamber having a movable wall, a bulb element communicating with said chamber, an electric heating element for said bulb element, a thrust member operable by said wall, a pivotally supported member engaged by said thrust member, means operatively connecting said pivotally supported member and said lever arm, said connecting means including a spring normally urging said pivotally supported member and said arm into engagement with each other, and a thermostat responsive to temperature created by said furnace and controlling said heating element.

16. A device of the character described, comprising a supporting member, motor means secured to the underside of said supporting member, said supporting member having an aperture therethrough, a rocker member pivotally mounted upon said supporting member, a thrust member extending through said aperture and operatively connecting said rocker member and said motor means, a lever having a fulcrum support, and means connecting said rocker member and said lever, said last-named means including a spring to permit relative movement between said lever and said rocker member.

1'7. A device of the character described, comprising a supporting member, motor means secured to the underside of said supporting member,

said supporting member having an aperture therethrough, a shaft carried by said supporting member, a rocker member pivotally supported by said shaft, a thrust member extending through said aperture and operatively connecting said rocker member and said motor means, a lever pivotally supported by said shaft, and means con necting said rocker member and said lever.

18. A device of the character described, comprising a supporting member, a casing member secured to the underside of said supporting connecting said thrust member and said rocker' member, a lever pivotally supported by said arms, and means operatively connecting said rocker member and said lever.

LEWIS W. EGGLESTON. 

